TURNER, HAENKE AND HUBBARD GLACIERS 101 glacier still expanded outside its mountain valley, as Turner Glacier does, but the southern wing seemed in 1910 and 1913 to no longer unite with the northern wing of the Turner, as it did in 1906. We could not, however, be certain of this, since the Haenke tip extends in behind the Turner and may be still united with it there. The changes in Haenke Glacier thus agree with those observed in the other glaciers which have advanced under the influence of earthquake shaking. The advance was abrupt, spasmodic and extensive, and it was completed in a very brief period. After being observed in the summer of 1906 the glacier evidently advanced little if any more, and since then ablation has proceeded with such great rapidity and effectiveness as to heal the crevasses that the spasmodic advance produced. The notable advance of the front has not been counterbalanced by recession, and cannot be for many years. We have given this glacier less thorough and close study than the other advancing glaciers, partly because of the difficulty of reaching it through the icebergs, but largely because prior to 1906 it had not presented phenomena of sufficient interest to warrant description and photographing from sites close enough at hand to permit more detailed comparative observations. As compared with the other glaciers that advanced in 1906 it is of interest primarily because of the very notable forward thrust of its front, which, up to the time of our observations on Hidden Glacier in 1909, was quite unprecedented in amount and rapidity. It is, therefore, rather unfortunate that we have no record of the exact position of its front before 1906. HTTBBABD GLACIBE General Description. Hubbard Glacier (PL XLII), one of the largest and grandest tidal glaciers on the North American continent, enters Yakutat Bay at the head of Disenchantment Bay. No photograph or description can do justice to the magnificence of this vast ice stream, which, having its source far back among the snow-covered mountains, flows with almost no stain of debris, as a pinnacled and crevassed flood of pure-white ice, deeply set in the mountain valleys, among lofty snow-capped peaks, and terminates in a lofty ice cliff from which icebergs are almost constantly falling. From every part of the fiord from which this glacier is visible it dominates the scene; yet, even when looking upon it from the most favorable viewpoint, and far more when looking upon a mere photograph of it, one cannot realize its size, for it is set in a mountain scene of such surpassing grandeur that even such a glacier is dwarfed by comparison. How large it is in reality may be inferred from the photograph of the glacier front on which is drawn to scale the Masonic Temple in Chicago (PI. XLHI, A), and from the map which compares this lower part of Hubbard Glacier with the whole of the Aletsch, Mer de Glace, and Rhone Glaciers in Switzerland (Fig. 6). Hubbard Glacier* has a total known length of twenty-eight miles along the north tributary, and is doubtless much longer, perhaps heading over forty miles to the north on a through-glacier divide with the Kaskawulsh Glacier north of the St. Elias Range. Besides this north ice tongue there is a broad tributary whose lower twelve and a half miles is all that has been seen by man; and there are two much narrower tributaries each at least twelve miles long, five other branches each over five miles long, and scores of smaller tributaries. The Hubbard Glacier system includes over 100 miles of known » Martin, Lawrence, The Hubbard Glacier, Alaska, Popular Science Monthly, Vol. LXXVI, 1910. pp. 293-805.